1. Field of the Invention
The present invention relates to a device and method for detecting an overlap of pulse signals and an apparatus for estimating a distance using the same, and more particularly, to a device and method for detecting an overlap of pulse signals, capable of easily detecting a point where a reference pulse signal and a delayed pulse signal overlap each other in an apparatus for estimating a distance which estimates a distance between distance estimating devices by counting pulses of the reference pulse signal generated at a point of transmitting a distance estimation signal and the delayed pulse signal generated at a point of receiving a response signal for the distance estimation signal, and the apparatus for estimating a distance using the same.
2. Description of the Related Art
In general, with a location awareness technology, wireless communication devices communicate wirelessly with each other using a wireless signal to estimate a current location thereof. Information obtained by the location awareness technology is significantly utilized to implement a more effective network.
To enhance accuracy of location awareness in this technology, it is of great importance to accurately detect a distance between two wireless communication devices. Typically, for distance estimation, the distance is calculated by detecting a time of arrival (TOA), i.e., time required for two wireless communication devices to transmit and receive a signal wirelessly. Also, the TOA is detected by counting certain pulses of pulse signals by a counter and utilizing this count value and frequencies of the pulse signals. The method for estimating a distance by counting pulses is disclosed in Korean Patent Application No. 10-2006-0090309, entitled “Apparatus and method for estimating distance using time of arrival”, which was filed on Sep. 18, 2006 by the same applicant.
In the method for estimating a distance between devices disclosed in the above document, a point where two pulse signals overlap each other is determined and then a distance between the devices is estimated based on the count value obtained by counting pulses of the two pulse signals up to the point of overlapping and frequencies of the pulse signals. FIG. 1 illustrates a conventional technology for detecting an overlap of two pulse signals used in the distance estimation method disclosed in the prior art document.
As shown in FIG. 1, to identify a portion where a first pulse signal P1 and a second pulse signal P2 having different frequencies overlap each other, the two pulse signals P1 and P2 are multiplied by each other, and when a pulse signal M1 is generated subsequently, it is determined that an overlap has occurred. That is, conventionally, the two pulse signals are multiplied by each other, and only when the first pulse signal P1 has a high value and the second pulse P2 has a high value, it is determined that the pulse signals overlap each other. In consequence, in the conventional method, when the pulse signals are overlapped in a very small portion, such an overlap is hardly detected.